In a second generation communications system, users' information exchange demands mainly focus on voice calls and short messages, which have a modest requirement for spectrum efficiency. The system is mainly restricted by the size of a coverage area. Therefore, a networking mode of macro base stations is generally used. The base stations are far from each other. This networking mode features a low cost. With the development of the third and fourth generation communications systems, data transmission has become a new demand, especially real-time transmission of video. This, however, has an increasingly high requirement for spectrum efficiency and network throughput. A macro base station covers a large area and is capable of serving a large number of users. Therefore, the throughput of the macro base station is greatly restricted. When the macro base station covers one or more densely-populated areas, an even higher requirement is presented for the macro network throughput. In this case, single-layer coverage of the macro base station only meets users' basic voice service demand, and cannot meet the high-speed data transmission demand. Obviously, the existing networking mode of the macro base station cannot meet users' demands for high-speed data transmission.
Considering the defect of the macro base station, a solution provided in the prior art uses a multi-layer heterogeneous network architecture involving both a macro base station and a pico base station at a hot spot (referring to FIG. 1A). The macro base station provides a large-scale continuous wide coverage, and the pico base station provides coverage for a hot spot area. Users access the macro base station in an area having only the macro base station network, and take precedence to access the pico base station in an area covered by both the macro base station network and the pico base station network, for offloading the traffic of the macro base station network and obtaining better services. The macro base station and the pico base station are two independent networks. When a user chooses to access a base station the base station establishes both a control plane connection and a data plane connection with the user, provides air interface radio transmission for the user, and assigns and maintains for the user a unique cell-radio network temporary identity C-RNTI (Cell-Radio Network Temporary Identity, cell-radio network temporary identity) under the base station for identifying an RRC (Radio Resource Control, radio resource control) connection and uniquely identifying the user in scheduling. When the user is handed over between base stations, a source base station sends context information of a user equipment such as the C-RNTI identity to a target base station over a backbone network; the target base station assigns a new C-RNTI identity to the user, and notifies the user of updating the C-RNTI identity over an air interface through the source base station; and the C-RNTI identity maintained by the source base station is released after a successful base station handover.
After analysis on the prior art, the inventors find that the prior art has at least the following disadvantages.
In the multi-layer heterogeneous network architecture, because the coverage area of a pico base station is small, during moving of the user equipment, each time the user equipment accesses a pico base station, the pico base station needs to assign a new cell-radio network temporary identity C-RNTI to the user equipment, and notify the user of updating the C-RNTI through radio transmission. This not only reduces the efficiency of the base station, but also increases information transmission of the backbone network and radio network and reduces the utilization rate of radio resources.